There's a version where you CAN use Cappy? Did I miss something?
On my first try, I wanted to use him but forgot he was stuck on the scarecrow.
So I just went to the lower level, got the moon and done.

I see. So some challenges got hard modes, so to say. I didn't play that much after completing the story, except for some new moons. Just got bummed you can buy infinite moons in the shops and thought I had to get "them all". Kinda broke my completionist heart. ^^'